Dermatofibrosarcoma protuberans – the use of neoadjuvant imatinib for treatment of an uncommon breast malignancy: a case report

BACKGROUND: Dermatofibrosarcoma protuberans is a rare soft tissue malignancy that, if left untreated, can be locally destructive and life-threatening. Dermatofibrosarcoma protuberans is uncommon in the breast, and the similarity of its morphologic features with other spindle cell malignancies can make correct identification difficult. Immunohistochemistry and molecular testing can aid in the correct diagnosis when there is diagnostic uncertainty. Imatinib, a selective tyrosine kinase inhibitor, has been used for adjuvant treatment of dermatofibrosarcoma protuberans following surgical resection. When used as a neoadjuvant treatment, imatinib offers the opportunity to decrease tumor size prior to surgery to lessen the chance for disfigurement. CASE PRESENTATION: We present the case of a Caucasian woman who was 46-year-old when she first noted a mass in her right breast in 2015; she was initially diagnosed as having metaplastic breast carcinoma. Mastectomy and systemic chemotherapy were planned; however, after review of pathology at a referral center, the diagnosis was changed to dermatofibrosarcoma protuberans. She was treated with 4 months of neoadjuvant imatinib with adequate tumor shrinkage to perform breast conservation. CONCLUSION: This patient’s case stresses the importance of correctly diagnosing this rare breast tumor through the histopathologic appearance of dermatofibrosarcoma protuberans, molecular pathogenesis, and immunohistochemistry. These techniques can help differentiate dermatofibrosarcoma protuberans from metaplastic breast carcinoma and other spindle cell lesions of the breast. This is critical, as the treatment options for metaplastic breast carcinoma significantly differ from treatment options for dermatofibrosarcoma protuberans. This case describes the use of imatinib as a neoadjuvant option to reduce preoperative tumor size and improve surgical outcomes.